Direct answer: The UK’s Be Ready guidance asks households to plan for three days. Here is what that means in watt-hours, which capacity tier covers phones, lights and a router, and why heating, cooking and kettles stay off the list.
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The 3-Day Power Budget: What a Portable Power Station Covers in a Be Ready Outage
The UK government's Be Ready campaign asks households to prepare for three days without normal services. Its wording is deliberate: "Being ready for 3 days helps you manage while support reaches those most in need." That has replaced the older "72 hours" shorthand, and it is a more useful number for anyone deciding how much backup power to own.
Three days is short enough to plan for and long enough that a phone power bank alone will not carry a household through it. This guide converts the official checklist into watt-hours, shows what each capacity tier actually covers, and is explicit about the loads a portable station should never be asked to run.
What the official checklist actually asks for
The Be Ready household guidance lists the items it expects people to keep. The power-related ones are modest:
- Light: "Torch (and spare batteries) — Torches are safer than candles."
- Information: "FM radio (battery / wind up)" — with a note to write down the frequencies you use.
- Communication: "Charged power bank — To charge phones or compatible medical devices."
- Water: "Bottled water for 3 days — 3 litres per person per day for drinking."
- Food: non-perishable food for three days that needs no refrigeration or cooking.
- Also listed: cash in mixed denominations, printed copies of documents, a first aid kit, essential medication, and contact numbers written on paper.
Notice what is absent: no generator, no power station, no home battery. The guidance is technology-neutral and deliberately modest, and that matters when you are deciding what to buy. A portable power station is a larger version of the "charged power bank" line, not a government requirement.
Turn the checklist into watt-hours
The arithmetic is the same one used in the power station sizing calculator: watts multiplied by hours gives watt-hours, and AC loads should be divided by roughly 0.85 to account for inverter losses.
| Load | Typical draw | Hours per day | Wh per day |
|---|---|---|---|
| Two phones (USB) | 10W | 3 | ~30Wh |
| LED torch or lantern | 4W | 5 | ~20Wh |
| Mains FM radio | 5W | 6 | ~30Wh |
| Wi-Fi router | 10W | 24 | ~240Wh |
| Laptop | 60W | 2 | ~120Wh |
| Fridge-freezer (cycling average) | 60–100W | 24 | ~1,400–2,400Wh |
On the checklist alone — phones, torch, radio — a two-person household needs roughly 80Wh a day, or about 240Wh across three days. That is one decent power bank and a spare.
Add a router and a laptop and the same household needs around 440Wh a day, or roughly 1.3kWh for three days. The checklist did not change. The optional loads did, and they are what turn a small purchase into a large one.
What each capacity tier really covers
| Capacity | Realistic three-day coverage | Honest limits |
|---|---|---|
| 300–500Wh | Phones, lights, radio, occasional laptop, small fan | No router for 72 hours, no fridge, no cooking |
| 700–1,000Wh | The above plus a router, a small TV, a CPAP machine on an approved DC cable | A fridge for a day at most; no heat |
| 1,500–2,000Wh+ | Phones, lights, router, laptop and a fridge-freezer kept closed | Still no heating, kettle or hob |
Once you have a capacity target, browse current power stations by capacity and compare live prices in the price comparison table. Capacity is only half the specification. Continuous AC output decides whether an appliance will start at all: a 1kWh station with a 500W inverter cannot run a 900W microwave regardless of its watt-hours. Check continuous and surge ratings before comparing prices.
What no portable station should be asked to do
- Heating. A 2kW fan heater flattens a 1kWh battery in half an hour. The guidance's answer is blankets, sleeping bags and warm clothing, and it is the right one.
- Cooking. Kettles draw 2.5–3kW and induction hobs more. A camping stove used outdoors is the conventional answer; never burn one indoors.
- A whole fridge-freezer for three days. A typical unit uses 1–2kWh a day. Keep the door shut and treat a station as a way to protect the contents for hours, not days.
- A gas boiler, without professional advice. A combi boiler's pump and controls often draw under 150W, but the boiler is hard-wired, not plugged into a 13A socket. Connecting one to a battery needs a competent electrician and a proper transfer arrangement — see grounding and earthing a power station for why this is not a DIY adapter job.
- Anything life-sustaining, unless the device manufacturer approves it. Device-specific planning is covered in power for medical equipment that must run 24 hours.
Recharge assumptions in a British winter
The plan has to assume no recharge, because the thing that failed is the mains. Solar is a poor winter bet: a 200W folding panel on a clear December day might produce a few hundred watt-hours at best, and often far less with low sun, short days and shading. Car charging is more dependable but slow — a 12V socket typically delivers around 100W, which is covered in charging from your car.
That is why the budget above is sized for three days with zero input. Treat solar as a way to extend a longer outage, not as a substitute for capacity.
A worked plan for two adults in a flat
| Load | Wh per day |
|---|---|
| Two phones | 30 |
| Lights | 20 |
| Radio | 30 |
| Router | 240 |
| Laptop (2 hours) | 120 |
| Total | 440 |
Three days is 1,320Wh. Add 15% for ageing cells, cold and inverter losses and the target is roughly 1,500Wh — a 1,500–2,000Wh class unit. Drop the router and laptop and the same household needs 240Wh for three days, which a 300–500Wh station covers with margin.
The difference between those two answers is one decision: whether staying connected matters more than the price and weight of the battery.
Buying order from a standing start
The guidance itself says "You don't need to do it all at once. Build up your readiness gradually over time." A sensible order is:
- Torches, spare batteries and a 20,000mAh power bank (about 70Wh of cells, less at the plug).
- A battery or wind-up FM radio.
- A 300–500Wh power station, tested with your actual devices.
- A 100–200W folding panel, if you have a realistic place to use it.
- A larger station only after logging a week of real loads rather than guessing.
FAQ
Is 500Wh enough for a three-day power cut?
For phones, lights, a radio and a laptop used sparingly, yes — that is roughly 240–400Wh over three days. It is not enough to keep a router running for 72 hours and still run a fridge.
Does the UK government recommend buying a power station?
No. The Be Ready checklist names a charged power bank and a battery or wind-up radio. A power station is a larger, more capable version of that power bank, not a published recommendation.
Can a power station run my gas boiler?
Possibly its electronics, but a boiler is hard-wired and needs a proper transfer arrangement installed by a competent person. Do not use a DIY lead to back-feed a ring main or boiler circuit.
How much solar would recharge a station in a winter outage?
Far less than the label suggests. Expect a few hundred watt-hours on a good winter day from a 200W panel, often less. Size the battery for three days without sun.
Should I leave the station plugged in between outages?
Only if the manufacturer specifies it. Most lithium units are happier stored at 50–80% in a cool, dry place, topped up every few months — the routine is covered in six-month readiness.
Turn the budget into a shortlist
The budget should decide the capacity, not the other way round. Work through these steps in order:
- Confirm the measured load with the power station sizing calculator.
- Compare live prices per watt-hour in the price comparison table.
- Shortlist two or three models at the capacity you actually need, then check continuous output and weight.
If the plan is phones, lights, radio and a router for three days, a 500Wh-class unit is the sensible starting point. Browse the full power station catalogue, or go straight to current ranges from EcoFlow, Bluetti, Anker SOLIX and Jackery.
If a fridge or medical equipment is on the list, size up before buying. The medical equipment guide covers the device-approval questions a product page will not answer.